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New Member

QoS - mls qos trust extend


When this command is configured on a 6500 interface without a Cisco IP phone attached, what happens to the QoS packet markings? Are they remarked to CoS 0, are they left as is, etc.? For instance, if just a PC or video conferencing unit is connected directly to the port.



Re: QoS - mls qos trust extend

This command allows you to extend the QoS boundry to beyond the switch port, to the next hop device. The full command would be "mls qos trust extend cos #" - this command instructs the switch ports to also instruct the Cisco Phone connected to mark any traffic connected to the Phone PC interface, to mark all traffic to 0. With the option to mark from 0 - 7, but you would not really want to.

If there is no phone attached - then the command is not used. If you have a VC unit or PC attached, they will ignore this. If they have the capability to mark there own traffic - the switch will apply that traffic to the QoS traffic plan, which would cause issues with what you are trying to do overall with QoS.


New Member

Re: QoS - mls qos trust extend

Ok thanks.

In this config, only "mls qos trust extend" shows up - no " cos #" after it. Must be the version of code.

Thanks again!